DE2311206A1 - COMPENSATION COUPLING OF INTERFERENCE FILTERS AND APPLICATION TO COLOR PHOTOGRAPHY AND COLOR FILM TECHNOLOGY - Google Patents

Description

Dipl.-Ing. Heinz Lesier. Potentonwolt D-8 Mönchen 81. Cosimostioße 81 · Teielon: (0811) 95 38 20

Armand Roux March 7th 1973

Paris, France L 10,000

L / wa

Compensating coupling of interference filters and application to color photography and color film technology

In many technical fields in which colored light is used, an essentially white light source is used used, with the help of filters different chromatic light beams are generated. In most cases a first geometric separation is made with the help of a semi-transparent mirror that has a direct and a generated reflected beam, each of these beams are split again in the same process can. The individual beams, which are geometrically divided in this way, can then be filtered chromatically and their intensity can be regulated individually by diaphragms or neutral gray wedges in the respective bundle of rays are arranged *

By remixing the individual chromatic beams controlled in this way, a light is obtained with variable chromatism depending on the respective intensity settings.

It is known that the use of two-color interference filters a simplification of such technical designs allows. Such an interference filter takes namely at the same time a geometrical separation and a chromatic one Separation before. Part of the beam is passed through

309849/0800

Dipl.-Ing. Heinz Lesser, Potentanwalt D -8 Munich 81, Cosiinostroße 81 Telephone: (0811) 95 38

the interference filter let through it at a 45 ° angle is arranged to the axis of the incident beam, and the other part is reflected at 90 °. The two bundles of rays have complementary chromatisms and their mixture represents the original one, depending on the area of application essentially white or already colored light.

It is known that such interference filters, which consist of thin layers j superimposed on a transparent lamella

exist, are calculated and executed approximately in such a way that one contains a predetermined curve of the chromatic separation when using the interference filter at an inclination of 45 ° relative to the axis of the beam. However, since the light sources cannot be point-shaped, the bundles of light rays to be separated are never parallel. The light rays have a mean direction and their inclination towards this axis lies between 0 and a certain "opening" £. Such a bundle of rays thus has an angle of incidence oc = 45 ° + £ or in general «. = i + £ on a two-color interference filter. The curve of the chromatic separation between the transmitted beam and the reflected beam is therefore a function of the angle oc, which is also determined experimentally. So far, this has resulted in a major error in the use of two-color interference filters: the transmitted or reflected beam bundles do not have a uniform color, but rather this varies continuously from right to left of the beam in the plane of symmetry of the system and symmetrically outside this plane.

Up to now, this error could only be reduced by using a second light source with very small dimensions and an extremely small opening, which is arranged at the focal point of a precisely corrected and expensive collimator . One could only have one light intensity

309849/0800

Dipl.-Ιης. Heinz Lester, Palentanwalt D - 8 Munich 81, Cosimastroße 81 Telephone: (0811) 95 38 20.

which was the smaller, the higher the evenness of the two should be separate bundles of rays.

According to the invention, an extended light source can be used at the focal point of a collimator, with for each point the light source a bundle of parallel rays with a variable inclination towards the central axis is formed .. Here there are two consecutive two-color filters of the axis and inclined in the opposite direction so as to offset the effects of the changes in inclination. The filters can be the same, in this case their opposite inclinations are both 45 °. Different filters can also be used. In this In the case of at least one of the angles is changed to a chromatically uniform, transmitted beam on the one hand and on the other hand to obtain the two reflected beams which are then reunited by known means, a chromatic beam being formed again which is present in the entire useful illumination field is substantially uniform.

The Kompeneierung achieved by the coupling of two interference filters can be further combined with colored in the mass correction filters that bring the Spektralverteilungskurven to ideal values differ ex in practice? · Hältenen curves of the light.

Further details of the invention emerge from the following description of an exemplary embodiment, with reference to the accompanying figures is referred to. It shows:

1 shows representations of spectral curves of the transmission of a two-color filter;

Fig. 2 is a schematic representation of the trichromatic division with the aid of two-color filters and the Reunification of the partial beams into one

309849/0800

Dipl.-Ing. Heinz lesser, ΡοΙοηΙαην, αΗ D - 8 Munich 81, Cosiinostrofk 81 Telephone: (0R11) 95 38 20

Light beam with a controlled main component / which illuminates an area of a film copier.

Fig. 1 shows in a continuous line the transmission curve of a filter reflecting the blue, dichrovex blue No. J. 4330, at an inclination of 45 °. The boundary part of the curve, which is its displacement, was drawn in a broken line towards the short wavelengths with increasing inclination of the filter against the axis of the light beam shows. An opposite shift takes place with a decreasing slope.

Fig. 2 shows the thread F of a light source at the focal point of a collimator 1, which the image of the light source in the Infinite sends. The parallel rays fall on a two-colored filger 2, which transmits the red light and enters blue and green bundles of rays reflected. An objective 3 focuses the red bundle of rays at FR. One lens 4 focuses a blue bundle of rays at FB after reflection on a two-color filter 5, which is the green bundle of rays passes, which is then reflected on a mirror 6 and is focused at FV. This will be on the schematic representation formed three colored bundles of rays with parallel axes. These three bundles of rays will be on a common optical axis 12 with the aid of a mirror 7 reflecting the red beam, a two-color mirror Filter 8, which transmits this red bundle of rays and reflects the blue bundle of rays, and a two-colored one Filter 9, which reflects the blue and the red and transmits the green, reunited with one another. One lens sends the images from FB and FR and a lens 10 sends the image from FV to infinity.

The three combined colored bundles of rays now illuminate the area 13 of a film copier. The chromatic

309849 / 080Q

Dipl.-Ing. Heim Lcsier, Pcitentanwolt D -6 Munich 81, Cosimoslraßo 81 · Telephone: (0811) 95 38 20

The uniformity of the illumination of this area in its width is ensured by three two-color compensation filters R, B, V reached, which are inclined against the first filters and each on the three separate paths of the blue, red and green bundle of rays are arranged.

In this application example, the compensation filters are only used to compensate for the bundles of rays that have passed through. The reflected residual beams are not used and are absorbed by black screens, not shown, in order to avoid interference from these rays.

The compensation filters are not used to compensate for the effect of a single main filter, but to compensate of the entire optical path used for all reflections and transmissions. For this purpose, on area 13 one after another each of the three colored beams is isolated by covering the other two, and becomes the The inclination of the compensation filter is changed until the chromatic uniformity of the illuminated area 13 is obtained.

In this way, when the three paths are chromatically compensated one after the other, each of the beams can with respect to the intensity by means of known devices not shown in the illustration, such as neutral gray wedges or diaphragms, are set, which are arranged, for example, in the respective levels of the images VF, VB, VR of the thread F.

The invention is not restricted to the application example described above and can be modified in various ways the type of division, filtration, combination and compensation of the beams.

309849/0800

Claims (7)

Dipt.-lng. Heinz Lesser, Potentonwalt D - 8 Münden 81, Cosirnastioße 81 Telephone: (0811) 95 38 20 "6 claims Optical system for separating light beams | with the help of at least one two-tone, transparent \ and reflective interference filter against the j Axis of the beam is inclined, g e k e η η - j characterized by at least a second j two-tone equalizing filter (R, B, V) located in axis j one of the separated bundles of rays with one of the ί inclination of the first filter (2,5) opposite
Inclination is arranged so that the angle of incidence at a beam inclined against the axis at an I. the filter increases and the other filter decreases. | 2. Optical system according to claim 1, characterized
characterized in that the first interference filter (2,5) and the compensation filter (R, B, V) are the same
and both are inclined by 45 relative to the optical axis
are. 3. Optical system according to claim 1, marked
net through several interference filters (2.5), which create several optical paths, each with
at least one compensation interference filter (R, B, V)
is provided, its inclination against the optical axis
is set so that the illumination and the chromatism of an area (13) illuminated according to this isolated optical path are balanced. 4. Optical system according to claim 3, characterized by means for changing the light intensity on at least one of the separated optical; Ways. 309849/0800 Dipl.-Ing. Hc-inz Ir'.wr, Potenlonwolt D -8 Munich 81, Cosimostroße 81 · Telephone: (0811) 95 38 20 5. Optical system according to claims 3 or 4, characterized by optical devices (7, 8, 9) for superimposing at least two of the separated beams. 6. Optical system according to claims 3 or 4, characterized by the combination of filters colored in the mass, which interact with the interference filters (2,5). 7. Optical system according to claim 5, characterized net by three bundles of rays, namely one red, a green and a blue bundle of rays, with adjustable intensity, which are at a common Windows for lighting a film copier are combined. 3098497Q800